Given a unity feedback system with open loop transfer function, $$$G\left(s\right)=\frac K{s\left(s+1\right)\left(s+2\right)}$$$ The root locus plot of the system is of the form.

Bode plot of a stable system is shown in fig. The transfer function of the system is

A unity feedback system has open-loop transfer function $$G(s) = {1 \over {s\left( {2s + 1} \right)\left( {s + 1} \right)}}$$

Sketch Nyquist plot for the system and there from obtain the gain margin and the phase margin.

A process with open-loop model $$G(s) = {{K{e^{ - s{\tau _d}}}} \over {\tau s + 1}},$$ is controlled by a PID controller. For this process